It is widely known to perform clustering of a network performing stream data packet transfer based on terminal relay-type multipoint communication, on a terminal basis.
An apparatus such as a rendezvous terminal constructing a stream relay path divides a communication terminal in a network into a plurality of clusters in advance. Upon receiving a participation request from a communication terminal (hereinafter referred to as “participant terminal”) wishing to newly participate in a session, this apparatus selects a parent terminal candidate for this participant terminal. Also, this apparatus measures bandwidth and delay among a participant terminal and parent terminal candidates, determines an appropriate parent terminal based on the measurement result, and reconstructs a stream relay path of a cluster including the parent terminal.
Especially in a large-scale network, by constructing a stream relay path on a cluster basis, it is possible to reduce a time required to measure the bandwidth and delay.
However, a large number of communication terminals belonging to one cluster cannot effectively reduce the time for measuring the bandwidth and delay. Also, a small number of communication terminals belonging to one cluster provides little flexibility for reconstructing the stream relay path, thereby making it difficult to receive a participant terminal. Thus, for example, patent document 1 discloses a technology to divide/integrate a cluster according to the number of communication terminals belonging to a cluster.
In the technique described in patent document 1, a super node arranged for each cluster monitors the number of communication terminals belonging to a cluster under monitoring. When the number of the communication terminals exceeds a first threshold, the super node determines to divide the cluster under monitoring. When the number of the communication terminals goes below a second threshold, the super node determines to integrate the cluster with other cluster. By this means, it is possible to promptly perform addition of a participant terminal.